Résumé:
Broiler coccidiosis is caused by coccidia parasites of the genus Eimeria spp, developing and multiplying in the gut of the chicken and causing either an acute deadly clinical form
manifested by bloody diarrhea, it is caecal coccidiosis caused by Eimeria tenella ; or
subclinical forms manifested by poor growth performance (weight index and consumption),
they are caused by several species, the most frequent Eimeria acervulina and Eimeria
maxima.
This work has been done on two studies:
1- The first, consists in carrying out a battery test on broiler chickens (Cobb 500), in
order to evaluate the resistance (or sensitivity) of a pool of field isolates (Jijel-Algeria)
containing the two species Eimeria acervulina and Eimeria maxima, against five
anticoccidial drugs (Diclazuril, lasalocid, monensin, narasin, salinomycin). The
anticoccidial sensitivity profile, based on the reduction of lesion scores compared to
non-infected non-medicated control and the anticoccidial index (ACI), reveals
complete resistance to monensin, narasin; partial resistance to salinomycin and
lasalocid, complete sensitivity to diclazuril.
2- The second study aimed to evaluate the efficacy and safety of two anticoccidial
vaccines, derived from local strains, against caecal coccidiosis, caused by Eimeria
tenella, in broiler chickens. The first is inactivated (by microwave radiation) while the
second is a live attenuated vaccine (attenuation by Ultraviolet-C). The safety and
efficacy of the two vaccines were tested separately on two separate experiments on
boiler chicks (Cobb 500) raised on floor. Two groups of chicks were vaccinated using
the prepared vaccine and challenged at day 20 of age. The first group was vaccinated
only once,at day 1 post hatching, the second group was vaccinated twice (day 1 and
day 8 post hatching). The study used two non-vaccinated control groups; the first
group was challenged with Eimeria tenella (50 000 sporulated oocysts/bird), while the
second remained uninfected. The evaluation criteria were body weight, feed
conversion ratio (FCR), blood in faeces, survival rate, lesion scores and oocyst output
per gram of faeces (OPG). In both experiments, the two vaccinated groups had an
overall better performance comparing to the non-vaccinated challenge group. In
conclusion, it seems that the two anticoccidial vaccines are effective in stimulating
protective immunity in vaccinated chickens against caecal coccidiosis. Although
vaccination with two divided doses seems more effective than immunization with a
single dose.
